Powered sprinkler

ABSTRACT

A rotary pop-up underground sprinkler which utilizes a selfcontained integrated gear case and nozzle section and a valve-inhead concept with a reverse flow valve. The entire gear case and nozzle assembly act as the piston of a hydraulic cylinder. When the reverse flow valve opens, hydraulic pressure builds up within the case and the area differential causes the piston to move upwardly. To retract the head, the reverse flow valve closes, dropping the pressure to atmospheric below the piston seal, and the high pressure from below the valve seat is directed through a communication tube to a point higher than the piston seal when the piston is fully extended, thereby hydraulically forcing or driving the gear case and nozzle assembly downwardly to its retracted position with the hydraulic pressure continuing when the sprinkler is fully retracted to hold the sprinkler in retracted position by hydraulic pressure. As an alternate form, the retraction power is provided by a spring. The entire valve is removable from the top, including the valve seat and the screening system protecting the valve.

Elite States atem 1 1 Hunter 111 3,713,584 1 Jan. 30, 1973 1 POWERED SPRINKLER [75] Inventor: Edwin J. Hunter, Riverside, Calif.

[73] Assignee: Toro Manufacturing Corporation,

Minneapolis, Minn.

[22] Filed: Feb. 16,1971 [21] Appl.No.: 115,599

Primary Examiner-M. Henson Wood, Jr.

Assistant Examiner-John J. Love Attorney-Vernon A. Johnson and Thomas A. Leennon iv A; E E

[ ABSTRACT A rotary pop-up underground sprinkler which utilizes a self-contained integrated gear case and nozzle section and a valve-in-head concept with a reverse flow valve. The entire gear case and nozzle assembly act as the piston of a hydraulic cylinder. When the reverse flow valve opens, hydraulic pressure builds up within the case and the area differential causes the piston to move upwardly. To retract the head, the reverse flow valve closes, dropping the pressure to atmospheric below thepiston seal, and the high pressure from below the valve seat is directed through a communication tube to a point higher than the piston seal when the piston is fully extended, thereby hydraulically forcing or driving the gear case and nozzle assembly downwardly to its retracted position with the hydraulic pressure continuing when the sprinkler is fully retracted to hold the sprinkler in retracted position by hydraulic pressure. As an alternate form, the retraction power is provided by a spring. The entire valve is removable from the top, including the valve seat and the screening system protecting the valve.

21 Claims, 14 Drawing Figures PATENTEUJAN 30 I973 SHEET 1 BF 3 sow/v BY THOMAS A. LENNON FIG. I

ATTORNEY PATENTEUJAN30 I973 3,713,584

SHEET 2 OF 3 INVENTOR.

48 I0 EDWl/VJ HUNTER FIG. 2 BY THOMAS A. LENNON ATTORNEY PATENTEDJANSO I975 SHEET 3 UP 3 m m 5 4 I 5 2 2 I G 9 O 7 8 W 6 0 6 II 6 6 N 5 1 5 f I |||I|\ I 3 Q I m l 7 .m 5 I N I w 7 mmnnmw m a i 4 A m k \M \\\\\\\y r//////////% I I I, F I w m w e u wm w m I I m I: mm

v MW B 7 N m f 8 MM EDW/A/ I! HUNTER BY THOMAS A. LENNON ATTORNEY POWERED SPRINKLER Valve-in-head rotary pop-up sprinklers have been available on the market for some time. However, those heretofore available have had some problems associated therewith. Two of the major problems associated with this type of sprinkler head have been that they are readily subject to being damaged, destroyed or stolen by vandals and that they frequently are prevented from fully retracting because of dirt or sand building up about the top of the casing.

Therefore, the primary purpose of this invention is to eliminate the aforementioned problems by providing a sprinkler head which can be forcibly retracted and held in retractive position by a force sufficient to eliminate or at least minimize vandalism thereof.

Another object of this invention is to provide the most suitable means for providing or effecting the powered retraction of the head, and the powered maintenance thereof in the retracted condition either by hydraulic means or by spring means, it having been found that the hydraulic form is more suitable for original equipment whereas the spring type appears more suitable for the replacement market.

Another object is to provide a sprinkler head which can be both raised and lowered by hydraulic means, one preferred embodiment of the invention involving an assembly which functions as a hydraulic piston and cylinder.

These and other objects and advantages will be more readily apparent and understood from the following description made in connection with the accompanying drawings in which like parts have the same numbers throughout the various views and in which:

FIG. 1 is a vertical central longitudinal sectional view of a hydraulically powered sprinkler head of this invention in retraction position;

FIG. 2 is a vertical, central longitudinal sectional view of the same sprinkler head in raised operative position;

FIG. 3 is an exploded view of the lower liner, gear case assembly, upper liner, and nozzle assembly utilized in the embodiment of FIG. 1 and 2;

FIG. 4 is an enlarged detailed sectional view of the valve and the piston seal when the head is retracted;

FIG. 5 is an enlarged detail sectional view of the piston seals when the head is extended:

FIG. 6 is a plan view of the oscillating drive gear set and its frame;

FIG. 7 is a top view showing the oscillating mechanism in one of its driving positions;

FIG. 8 is a top view showing the oscillating mechanism in its other driving position;

FIG. 9 is a cross sectional view through the web structure taken along the line 9-9 of FIG. 1;

FIG. 10 is a bottom plan view of the lower liner;

FIG. 11 is a cross sectional view taken on the line ll1l of FIG. 1, (with the gear assembly G not shown);

FIG. 12 is a view in partial vertical section of an alternate spring-loaded form of the invention in extended position;

FIG. 13 is the sprinkler head of claim 12 in fully retracted position;

FIG. 14 is an enlarged detail sectional view of a portion of the head when in fully extended position.

Referring to the drawings, the form of the invention illustrated in FIGS. 1 and 2 include a cylindrical outer housing or shell 10, the lower or bottom end of which is closed except for an internally threaded inlet 10a, said 5 shell being formed of plastic material in one preferred form.

Immediately above the inlet is a reverse flow valve assembly which will be considered in more detail hereinafter, and above the valve is a gear case assembly G and a nozzle assembly N which functions together as a unit as a vertically movable piston within the housing 10. The gear case forms the lower portion of the assembly and includes a cylindrical housing or casing 11 which is preferably made of stainless steel to withstand abuse and corrosion.

Housed within the gear case is the drive system for effecting the rotation of the nozzle. The basic design and functioning of this drive system is similar to that set forth in detail in U.S. Pat. No. 3,107,056, the details of which, for purposes of convenience, are incorporated in this application by reference. However, it is considered desirable to briefly describe this drive system as presented herein, which drive system includes a lower perforated plate 12 for admitting water to the interior of the gear case. A shaft 13 supports a turbine wheel 14 immediately above the perforated plate 12, so that the upwardly flowing water from the plate 12 engages and drives the turbine wheel. The upper end of shaft 13 is provided with an initial drive gear 15. Gear shafts l6 and 17 are provided which support a gear train comprising a plurality of gear units 18 (four units are illustrated), each gear unit consisting of a pinion gear element l9 and a spur gear 20, with the exception of the first gear unit, in which the larger lower gear 20 is a ring gear with the drive gear engaging the internal teeth thereof.

The gear units revolve on their respective shafts with the pinion gear elements of preceding gear units engaging the spur gear elements of succeeding gear units.

The final drive system includes a shaft 21, the lower end of which has drivingly mounted thereon a gear 22 which is driven by the aforementioned and aforedescribed drive train. The upper end of drive shaft 21 is provided with a final drive gear 23, which gear serves to rotate the nozzle during operation in a manner hereinafter described.

The nozzle system includes a sprinkler tube 24 which is supported by structure 25 for relative rotation of the tube with respect to said supporting structure. An 0- ring seal 26 is provided which surrounds the lower end of the tube and is interposed between the tube and said supporting structure.

The upper end of the sprinkler tube is externally threaded as at 27 for attachment to the upper nozzle assembly N. This upper nozzle assembly N includes an inverted cup-shaped cylinder 29 which is closed at its upper end by horizontal top portion 29a. A pair of nozzles 30 are mounted inside the cylinder 29 and are positioned to discharge streams of water through a pair of openings 31 in the side wall of the cylinder 29. Interiorally of the cylinder 29, and beneath the nozzles, an inverted cup-shaped mounting member 32 is provided which has an internally threaded central opening 32a, said opening permitting water to be admitted to the interior of cylinder 29 from tube 24 for spraying by the nozzles, said threaded opening being screwed on the upper threaded end 27 of the sprinkler tube 24 so that the two can rotate simultaneously.

The casing 11 has a reduced upper end portion 11a. The reduced upper end portion has an opening formed therein through which the tube 24 extends, an annular upper sealing member 34 which surrounds said tube being provided, said seal 34 being interposed between said tube 24 and reduced portion 11a in sealing relationship therebetween, whereby the tube 24 is free to rotate relative to said seal, and said casing. The lower end of the casing 11 is provided with an out-turned annular circular flange 11b which supports an annular sealing member 35 which surrounds said casing, said seal being held in position by an annular collar 36, said seal being interposed between casing 11 and liner 38, and in wiping sealing engagement with said liner. Another and slightly larger sealing member 37 also encloses the casing 11, and in interposed between casing 11 and housing and is in wiping sealing engagement with said housing 10, with the collar 36 serving as a stop for the travel of the upper seal 37 and liner 51 and a spacing member between the seals 35 and 37.

The aforementioned nozzle system reciprocates and operates within a cylindrical inner sleeve or liner 38 located within the outer shell or housing 10. This liner 38 is seated and rests on an internal shoulder 10b of the housing 10. The liner has an internal annular portion 39 which defines a circular opening 40, the lower marginal edge of the opening defining a valve seat 41. The liner is spaced from the housing to provide an annular chamber 42 between the housing 10 and liner 38 for receiving fluid for retracting the piston in a manner hereinafter described.

The lower portion of the liner includes a reduced cylindrical portion 43 for housing the control valve. The reduced portion 43 is spaced from housing land forms therewith a fluid chamber 28. The valve cylinder 43 has a depending cylindrical portion 43a of smaller size with a central bore or opening therein for admitting fluid to and discharging it from the valve pressure chamber. A multiplicity of vertical, laterally spaced apart fins 44 extend between the reduced portion 43 and the main wall of the liner 38 and connect the reduced portion with the wall of the liner 38 to admit water from the main system into the interior of the liner 38, the admission of fluid taking place through the openings 45. Fins 44 serve the additional function of a screen to protect the valve from particles which could jam in the valves or the nozzles. A vertical slot 46 is provided in the main wall of the liner below the annular portion 39 and between two adjacent fins to permit fluid from the main line to escape through fluid -chamber28 into the chamber 42 when the control valve is closed.

The upper end of liner 38 is provided with an annular rib 47 which serves as a spacing element for maintaining the liner in spaced relationship with respect to the housing 10.

The spacing rib 47 has four openings or slots 48 formed therein which are equally spaced about the perimeter of the rib, and are intended to permit fluid to escape from the chamber 42. The upper marginal edge of the liner is provided with four vertical slots 49 which extend downwardly from the upper margin thereof, and

are in physical alignment with the openings 48, said slots 49 being intended to receive the fluid escaping from the openings 48.

The fluid from the slots 49 is admitted into an annular chamber 50 which is the area defined between the seals 35 and 37, and the collar 36 and the liner 38, the pressure of the fluid so admitted on the seals 35, driving the piston downwardly from its raised position to a fully retracted position when the control valve is closed.

The upper portion of the sprinkler head is provided with an upper liner 51 which is cylindrical in form, and is concentrically positioned within the housing 10, said liner having a lower internal annular foot 51a which rests upon the seal 37 and holds it in position. Said upper liner has an external rib 52 which rests upon the upper marginal edge of the housing 10. Saidrib 52 is provided with a positioning opening 53 which receives an upstanding positioning tab 54 carried by the upper marginal edge of the housing 10. The liner 51 is locked in position by a cap 55 which threadedly engages the upper threaded portion of the housing 10, said cap having an opening to permit the nozzle system to extend therethrough, an annular seal 56 being provided between said cap and said nozzle system, said seal enclosing and sealingly engaging the nozzle cap .29, said seal being held in place against the upper end of liner 51 by the upper internal flange 55a of the cap 55.

Thus, the gear case assembly G which serves as a piston slides up and down within the stationary enclosure, in sealed relationship with the lower liner 38, carrying the nozzle assembly N with it, said sealed relationship being provided by the seal 35.

A reverse flowor control valve 57 is located within the lower reduced portion 43 of the lower liner 38 and slides up and down with respect thereto in sealed relationship therewith, the seal being provided by an annular sealing member 58 forming an integral part thereof which sealingly engages the inner wall of the reduced portion of the liner. The valve 57 and valve cylinder 43 define therebetween a valve pressure chamber 33. If pressurized fluid is admitted to said chamber 33, the valve closes. If the pressure is relieved, the valve is opened by fluid pressure pushing downwardly on the upper face of seal 58. Said control valve 57 is continuously biased towards closed position by means of a helical compression spring 59 which bears against the lower wall of the reduced portion of the liner, and also against the interior of the valve itself. The spring 59 is coiled about mating spring guides 77 and 78 on the control valve and the reduced portion respectively. The upper portion of the valve has an annular shoulder 57a which constitutes a traveling valve seat which cooperates with the stationary valve seat 41 when the valve is closed.

The lower portion of the housing has an internal cylindrical portion 60 which is connected with the main portion of the housing by a pair of oppositely extending web members 61, one of said web members having an internal fluid control opening 62 formed therein, said control opening 62 being in fluid communication with a control fitting or nipple 63, carried by the housing 10.

The internal cylinder 60 receives and supports a fitting 64 having a passageway 64a therein to provide communication between the nipple 63 and the pressure chamber 33 of the control valve.

The rotation is accomplished by means of a hub member 65 attached to the sprinkler tube and rotatable therewith, said hub including a radial disc 65a terminating in an annular skirt 65b, the internal face of which is provided with an internal gear 66 which is driven by the gear 23 in the manner hereinafter described, the driving of gear 66 in turn rotating the hub 65, which in turn rotates the tube 24, which in turn rotates the nozzle assembly N.

Mounted within the hub 65 is an oscillatory drive. The oscillatory drive includes an arcuate bottom plate 80 from which extends two spaced arms 81 which encircle the tube 24, and an arcuate top plate 82. Between the bottom and top plates 80 and 82, is a gear set which includes gear 23 mounted on the shaft 21. A pair of idler gears 83 and 84 are mounted at one side of the drive gear 23. The idler gear 84 drives a terminal gear 85 which is engageable with the teeth of the internal ring gear 66 to drive the internal gear and with it the sprinkler tube and nozzle assembly in one direction, for example, a clockwise direction. The other side of the drive gear 23 is engaged by an idler gear 86 which in turn drives a second terminal gear 87. The second terminal gear 87 is also engageable with the gear teeth of the internal gear 66 to drive said gear and with it the sprinkler tube and nozzles in the opposite direction, for example, in a counterclockwise direction.

The oscillatory drive is so mounted that when oscillated to one extreme position one terminal gear is in operation and when operated to the opposite extreme position, the other terminal gear is in operation. Oscillatory movement is accomplished by a trip member 88 which includes a collar 89 journaled on the sprinkler tube and a radial trip arm 90.

The trip arm 90 is adapted to move arcuately between stops 91. The spacing between the extremities of the arms 81 in such that the trip arm engages one or the other of the arms 81 before engaging a corresponding stop 91, and oscillates the drive to bring one or the other of the terminal gears 85 or 87 into operation as best shown in FIGS. 4 and 5.

The trip member 88 is urged to one extreme position or the other by means of a pair of over-center springs 92. Each over-center spring is semicircular in form with radially outwardly extending serrated lips. On lip of each spring bears against the collar 89 between bosses 93 and the other lip of each spring engages lugs 94.

The aforedescribed oscillatory drive is similar to that described and illustrated in more detail in US. Pat. No. 3,107,056 and for a more elaborate discussion of this structure and operation thereof, the reader is referred to said patent. The actual oscillatory mechanism is not critical to the operation of the sprinkler head of this particular invention and a variety of different mechanisms may be employed, the one herein described and illustrated being presented primarily to provide one working form of the invention.

The general operation of the aforedescribed sprinkler head is as follows. Assuming that the sprinkler is in the retracted position of FIG. I, the control valve 57 is closed and fluid pressure is bearing downwardly on the seal 35 through the fluid in chamber 50, and 42, said fluid being in fluid communication with the main fluid in the line entering the head through inlet a, so that the line pressure is being asserted downwardly on the seal 35.

The fluid entering through inlet 10a flows past the webs 61 into the annular space 28 and then proceeds upwardly between the fins 44 and then radially lnwardly through the openings 45 and then downwardly against the upper face of valve seal 58. Since the valve is closed, the fluid cannot escape upwardly through opening 40 to apply any upward pressure against the piston assembly. The valve pressure chamber 33 is filled with pressure fluid which is equal or above the pressure of the fluid at the inlet 10a and which is being applied against the top face of seal 58. The fluid pressure in the valve chamber is applied upwardly against the lower face of seal 58, thereby at least neutralizing, and in some instances overcoming, the downward pressure on the seal 58. The spring 59 overcomes any pressure differential on the seal, and drives the valve 57 upwardly into closed position against the stationary valve seat 41.

Since the fluid cannot escape upwardly through opening 40 when the valve is closed, it escapes from space 28 between a pair of fins through slot 46 into the annular chamber 42 between liner 38 and housing 10, from where it escapes upwardly through the four openings 48 in the rib 47, and then proceeds through the slots 49 in the top of the lower liner into the annular chamber defined by the seals 35 and 37, where it builds up fluid pressure on the top of seal 35 and presses the seal and with it the entire piston assembly downwardly and positively holds it in fully retracted position.

To extend and raise the nozzle and effect operation of the sprinkler, pressure fluid is bled from the valve pressure chamber 33, behind the control valve, reducing the pressure behind the valve to atmospheric, relieving the closing fluid pressure behind the control valve and permitting the fluid line pressure asserted on the seal 58 by the fluid entering through the slots 45 to force the control valve downwardly away from the valve seat to the fully opened position of FIG. 2. The fluid thereupon enters the interior of the lower liner through'the opening 40, and bears against the lower face of the piston, and the area differential behind the upward and downward fluid forces pushes the piston assembly physically upwardly to the raised extended operative sprinkling position of FIG. 2. The fluid also passes through the lower perforated plate 12, and drives the turbine wheel 14, which in turn drives the aforedescribed gear train, which in turn causes the sprinkler tube to rotate, the fluid after leaving the gear train passing upwardly through the sprinkler tube and being discharged from the nozzles 30.

The alternate spring-loaded form of the invention is illustrated in FIGS. 12 and 13. In this version, the majority of the sprinkler head is as previously described, except for the face that in this version the head is retracted under the influence of a helical spring, rather than under the influence of hydraulic pressure as in the previously described version of this invention, and has no reverse flow control valve.

In this modification, a similar housing 10 is used, but the reverse flow valve system including the control valve 57, fittings 64, and nipple 63 are missing. The entire piston portion including the gear case assembly G and the entire drive assembly therewithin, and the nozzle assembly N attached thereto are identical to those previously described, with the exceptions hereinafter noted.

Thus, the entire head is raised by the upward fluid pressure entering through inlet 10a and bearing against the lower face of the piston assembly.

l-IOwever, to retract the head, an inverted cupshaped plastic extension 67 is secured to the bottom of the casing 11, said extension having a laterally extending annular flange 68 which engages and supports a helical spring 69 which is coiled around the casing 11 and the extension 67. A plastic collar 70 encircles the upper part of the casing 11, said collar having an annular laterally extending flange 71 against which the upper end of the spring 69 engages and works. A sea]- ing ring 72 rests on the collar 70 and is in wiping sealing engagement with the interior wall of the housing 10, and in sealing engagement with the casing 11. A snap collar 73 is mounted on the outer shoulder of the casing 11, said collar having a tab 74 which is seated in the vertical channel on the interior wall of the upper liner defined by the vertical ribs 75. The form of the invention of FIG. 1 also utilizes the collar 73 with its tab 74 operating in the channel defined by ribs 75, and in each instance this structure prevents the gear case assembly from rotating.

Thus, when the head is raised to extended operative position by subjecting the piston assembly to the line pressure, the piston is raised against the influence of the spring 69, thereby increasing the tension thereon. When the line pressure is reduced or shut off, thereby returning the pressure beneath the piston assembly to atmospheric, the tension in the spring 69 is sufficient to push the piston assembly downwardly and retract same to the retracted position illustrated. The extension 67 of the spring-loaded version is closed at the bottom by a filter screen member 76 which is removably press fitted into the extension.

In the illustrated version, the pressure chamber 33 of the control valve 57 has no direct communication with the upstream side of the valve. However, it will be understood that a metering or pin type of valve, such as those illustrated in my US. Pat. No. 3,315,696 may be substituted for the valve 57 illustrated and described herein. In the metering version, the valve pressure chamber is in communication with the upstream side,

and the fluid pressure therefrom serves as the means for closing the valve.

It will also be noted that the entire gear train is sealed off from direct contact with the water passing through the head. The majority of the drive system above the turbine wheel is enclosed by structure which includes a base 95 in which the shaft 13 and the lower ends of the shafts l6 and 17 are journaled, and an inverted cupshaped shell including side wall structure 96 and top wall structure 97 in which the upper ends of the shafts l6 and 17 are journaled. Thus, the shafts 13, 16, and 17 and the gear train from the initial drive gear 15 through the lower drive gear 22 are enclosed within the aforedescribed shell structure formed by 95, 96, and 97, and are isolated from the fluid stream, the shell structure being spaced from the stainless steel case 11 so that the fluid, after leaving the turbine wheel, flows around the outside of the shell and into the sprinkler tube 24. The shaft 21 is enclosed and isolated from the fluid by wall structure 98 which is integrally connected with the tube supporting structure 25, the structure 98 and 25 depending from and being integral with an inverted cup-shaped plastic sealing and supporting member which includes a circular top wall 99 which encloses the tube 24 and extends radially to the interior wall of the casing 11, and a depending cylindrical skirt 100 which also engages the interior wall of the casing 11, said cup member preventing flow of fluid into the upper reaches of the gear case where the final oscillating drive is located and forcing the fluid into the sprinkler tube.

The sprinkler head of this invention is especially suitable for use in extremely sandy conditions. It can be installed in the sand so that when retracted it will be below the level of the sand, or ground level, and need not be installed so that it sticks above ground level where it might be stumbled over or run into by vehicles, mowers, etc.

It will be noted that when the nozzle assembly is extended and rotating, it is only the nozzle assembly N and sprinkler tube 24 which rotate. The gear case 33 and its contents, (except for the sprinkler tube) do not turn when the nozzle is turning.

Thus, a sprinkler head having an axial flow rotor has been provided, which permits the fluid to move upwarclly straight through the head, sprinkler tube, and nozzles.

The valve construction provides for easy assembly and the useof the screening of filtering vanes or fins to minimize fouling and plugging of the system.

The heads are tamper proof because they are retracted to a point where there is no structure exposed which can be readily grabbed onto or openings which can be plugged, and the positive hold down force of the fluid or spring prevents the nozzle system from being raised.

The nozzle assembly N and gear case assembly G have the same diameter, and have cylindrical sections which are greater in length than the pop-up stroke required.

In the spring-loaded version of FIGS. 12 and 13, it will be noted that the cap 55' and seal 56' are of slightly different shape than their counterparts 55 and 56 respectively, although they function in essentially the same manner as said counter parts. Thus, although both seals 56 and 56 are of inverted cup-shape, the seal 56 has a much longer side wall of skirt which encircles the entire upper wall portion of the upper liner 51 above its rib 52, and has a laterally extending annular flange which rests on the rib 52 and is held thereagainst by the inturned upper end of the cap 55'. The cap 55' does not extend upwardly as far as cap 55, and does not overlap the upper marginal edge of the upper liner as does cap 55.

It will be understood that the sprinklers herein described having a control valve, such as the version illustrated in FIG. I, normally is installed in a system in which the fluid pressure is on at all times and there is pressure fluid in the inlet opening 10a at all times.

The gear case 11 and the nozzle case 29 are preferably of circular cross-section and of the same diameter. This avoids displacement of fluids within the annular chamber between the casings 11-29 and the upper liner 51 as the casings move up and down therewithin, and thereby avoids any pumping action in said chamber which might be caused by said casing movement.

The casings 11 and 29 also have cylindrical sections greater in length than the pop-up stroke required to enable them to operate properly within the sealing systems and to enable the seals to be retained at all times within the casing.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of this invention.

What is claimed is:

l. Sprinkler mechanism comprising:

a cylinder,

a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions,

said piston assembly being adapted to be moved from the retracted to the extended position under the influence of fluid pressure applied thereto,

said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means,

means for admitting fluid to said cylinder to operate said piston assembly,

and means for applying a retractive fluid force to said piston assembly to retract said piston assembly.

2. The sprinkler of claim 1, including means for continuing the application of said retractive fluid force on said piston assembly after it has reached said retracted position.

3. The sprinkler of claim 1, including valve means for admitting pressure fluid to said cylinder.

4. The sprinkler of claim 3, including means operative when said piston extending fluid pressure is reduced to apply fluid pressure to said piston assembly to retract same.

5. The sprinkler of claim 3, including means operative when said valve means is closed to channel fluid from the upstream side of said valve means to a location where it can apply retractive fluid pressure to said piston assembly.

6. The sprinkler of claim 3, wherein said valve means comprises a reverse flow valve.

7. The sprinkler of claim 1, wherein said piston assembly includes a cylindrical non-rotatable gear case section and a rotatable cylindrical nozzle section,

said sections being of the same diameter.

8. Sprinkler mechanism comprising:

a'tubular housing,

a cylinder within said housing and laterally spaced therefrom to provide an annular chamber,

a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions under the influence of fluid pressure applied thereto, said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means,

movable sealing means between said piston assembly and cylinder,

stationary sealing means between said piston assembly and cylinder,

said movable and stationary sealing means defining a fluid pressure chamber,

said movable sealing means being adapted to move said piston assembly downwardly towards the retracted position when fluid pressure is applied to the upper face of said seal by fluid in said pressure chamber,

means providing fluid communication between said annular chamber and said pressure chamber,

valve means for admitting pressurized fluid to said cylinder to apply fluid pressure upwardly against said piston assembly for extending the same,

means providing fluid communication between the upstream side of said valve means and said annular chamber,

and means for applying retractive force to said piston assembly when said fluid pressure is reduced.

9. The sprinkler of claim 8, including a second cylinder disposed within said housing and above said first cylinder,

said stationary sealing means being interposed between said cylinders, resting atop said first cylinder and being held thereagainst by engagement with said second cylinder,

cover means threadedly engaged with said housing and holding said second cylinder in fixed positio within said housing,

and second stationary sealing means interposed between said cover means and said piston assembly.

10. The sprinkler of claim 9,

wherein said piston assembly comprises an upper rotatable nozzle section including said nozzle means and a lower non-rotatable gear case section housing gear means for rotating said nozzle section, i

the majority of said gear case section being confined within said first cylinder and the majority of said nozzle section within said second cylinder and the majority of said nozzle section within said second cylinder when said piston assembly is fully retracted.

11. The sprinkler of claim 10, including guide means carried by one of said cylinders,

and guide means carried by said gear case section,

said guide means cooperating to permit free guided movement of said assembly axially of said housing while preventing rotation of said gear case section relative to said cylinders.

12. The sprinkler of claim 11, including a sprinkler tube rotatably supported in said gear case section and extending upwardly therefrom,

said nozzle section being attached to the upper end of said sprinkler tube and rotatable therewith,

said gear means being drivingly connected with said sprinkler tube for rotating same.

13. The sprinkler of claim 12, wherein said gear means are isolated from the fluid passing through said piston assembly.

14. The sprinkler of claim 8, wherein the lower end of said first cylinder includes structure defining an opening for admitting fluid to said first cylinder and also defining an annular stationary valve seat,

a valve cylinder below said opening and valve seat,

a piston valve in sealing movable engagement with said valve cylinder providing a movable valve seat for cooperating with said stationary valve seat to open and close said opening,

a plurality of laterally spaced fins between said valve cylinder and first cylinder defining a plurality of passageways for admitting fluid from the upstream side of said valve to the downstream side thereof including said opening,

said valve and valve cylinder defining therebetween a valve pressure chamber,

spring means within valve pressure chamber continuously biasing said valve towards closed position,

and means providing fluid communication between said pressure chamber and a point outside said housing for admitting fluid to and removing it from said pressure chamber.

15. The sprinkler of claim 14, including an opening in the lower end portion of the wall of said first cylinder adjacent said fins and providing the fluid communication between the upstream side of said valve means and said annular chamber between said first cylinder and housing.

16. Sprinkler mechanism comprising:

a cylinder,

a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions,

said piston assembly being adapted to be moved from retracted to extended position under the influence of fluid pressure applied thereto,

said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means,

means for admitting fluid to said cylinder to operate said piston assembly,

means for applying retractive force to said piston assembly when said fluid pressure is reduced,

first spring seat means carried by said piston assembly,

second spring seat means connected with said cylinder,

helical spring means coiled about said piston assembly and engaged with both of said spring seat means for biasing said assembly from extended to retracted position,

said first spring seat means is provided by an annular laterally extending flange connected to said piston assembly, and engaged by said spring,

said second spring seat means is provided by an annular member encircling said piston assembly which is slidable relative thereto,

said member having an annular laterally extending flange engaged by said spring. 1

17. The sprinkler of claim 16, wherein said retraction means comprises spring means.

18. The sprinkler of claim 17, wherein said spring means continues to apply positive pressure on said piston assembly in the direction of retraction after the piston assembly has reached said retracted position.

19. The sprinkler of claim 16, including an annular sealing member enclosing said piston assembly and sealingly interposed between said assembly and said cylinder,

and means connected with said cylinder for holding said sealing member.

20. The sprinkler of claim 19,

wherein said holding means includes a second cylinder disposed within said first cylinder and above said sealing member, the lower end portion of said second cylinder engaging said sealing member and holding it against movement,

and means interconnecting the two cylinder and holding said second cylinder against movement.

21. Sprinkler mechanism comprising:

a tubular housing,

a cylinder within said housing and laterally spaced therefrom to provide an annular chamber,

a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions under the influence of fluid pressure applied thereto, said piston assembly including nozzle means and means for passing through said assembly to said nozzle means,

movable sealing means between said piston assembly and cylinder,

stationary sealing means between said piston assembly and cylinder,

said movable and stationary sealing means defining a fluid pressure chamber,

said movable sealing means being adapted to move said piston assembly downwardly towards the retracted position when fluid pressure is applied to the upper face of said seal by fluid in said pressure chamber,

means providing fluid communication between said annular chamber and said pressure chamber.

valve means for admitting pressurized fluid to said cylinder to apply fluid pressure upwardly against said piston assembly for extending same,

and means providing fluid communication between the upstream side of said valve means and said annular chamber.

I II! t l 

1. Sprinkler mechanism comprising: a cylinder, a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions, said piston assembly being adapted to be moved from the retracted to the extended position under the influence of fluid pressure applied thereto, said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means, means for admitting fluid to said cylinder to operate said piston assembly, and means for applying a retractive fluid force to said piston assembly to retract said piston assembly.
 1. Sprinkler mechanism comprising: a cylinder, a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions, said piston assembly being adapted to be moved from the retracted to the extended position under the influence of fluid pressure applied thereto, said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means, means for admitting fluid to said cylinder to operate said piston assembly, and means for applying a retractive fluid force to said piston assembly to retract said piston assembly.
 2. The sprinkler of claim 1, including means for continuing the application of said retractive fluid force on said piston assembly after it has reached said retracted position.
 3. The sprinkler of claim 1, including valve means for admitting pressure fluid to said cylinder.
 4. The sprinkler of claim 3, including means operative when said piston extending fluid pressure is reduced to apply fluid pressure to said piston assembly to retract same.
 5. The sprinkler of claim 3, including means operative when said valve means is closed to channel fluid from the upstream side of said valve means to a location where it can apply retractive fluid pressure to said piston assembly.
 6. The sprinkler of claim 3, wherein said valve means comprises a reverse flow valve.
 7. The sprinkler of claim 1, wherein said piston assembly includes a cylindrical non-rotatable gear case section and a rotatable cylindrical nozzle section, said sections being of the same diameter.
 8. Sprinkler mechanism comprising: a tubular housing, a cylinder within said housing and laterally spaced therefrom to provide an annular chamber, a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions under the influence of fluid pressure applied thereto, said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means, movable sealing means between said piston assembly and cylinder, stationary sealing means between said piston assembly and cylinder, said movable and stationary sealing means defining a fluid pressure chamber, said movable sealing means being adapted to move said piston assembly downwardly towards the retracted position when fluid pressure is applied to the upper face of said seal by fluid in said pressure chamber, means providing fluid communication between said annular chamber and said pressure chamber, valve means for admitting pressurized fluid to said cylinder to apply fluid pressure upwardly against said piston assembly for extending the same, means providing fluid communication between the upstream side of said valve means and said annular chamber, and means for applying retractive force to said piston assembly when said Fluid pressure is reduced.
 9. The sprinkler of claim 8, including a second cylinder disposed within said housing and above said first cylinder, said stationary sealing means being interposed between said cylinders, resting atop said first cylinder and being held thereagainst by engagement with said second cylinder, cover means threadedly engaged with said housing and holding said second cylinder in fixed position within said housing, and second stationary sealing means interposed between said cover means and said piston assembly.
 10. The sprinkler of claim 9, wherein said piston assembly comprises an upper rotatable nozzle section including said nozzle means and a lower non-rotatable gear case section housing gear means for rotating said nozzle section, the majority of said gear case section being confined within said first cylinder and the majority of said nozzle section within said second cylinder and the majority of said nozzle section within said second cylinder when said piston assembly is fully retracted.
 11. The sprinkler of claim 10, including guide means carried by one of said cylinders, and guide means carried by said gear case section, said guide means cooperating to permit free guided movement of said assembly axially of said housing while preventing rotation of said gear case section relative to said cylinders.
 12. The sprinkler of claim 11, including a sprinkler tube rotatably supported in said gear case section and extending upwardly therefrom, said nozzle section being attached to the upper end of said sprinkler tube and rotatable therewith, said gear means being drivingly connected with said sprinkler tube for rotating same.
 13. The sprinkler of claim 12, wherein said gear means are isolated from the fluid passing through said piston assembly.
 14. The sprinkler of claim 8, wherein the lower end of said first cylinder includes structure defining an opening for admitting fluid to said first cylinder and also defining an annular stationary valve seat, a valve cylinder below said opening and valve seat, a piston valve in sealing movable engagement with said valve cylinder providing a movable valve seat for cooperating with said stationary valve seat to open and close said opening, a plurality of laterally spaced fins between said valve cylinder and first cylinder defining a plurality of passageways for admitting fluid from the upstream side of said valve to the downstream side thereof including said opening, said valve and valve cylinder defining therebetween a valve pressure chamber, spring means within valve pressure chamber continuously biasing said valve towards closed position, and means providing fluid communication between said pressure chamber and a point outside said housing for admitting fluid to and removing it from said pressure chamber.
 15. The sprinkler of claim 14, including an opening in the lower end portion of the wall of said first cylinder adjacent said fins and providing the fluid communication between the upstream side of said valve means and said annular chamber between said first cylinder and housing.
 16. Sprinkler mechanism comprising: a cylinder, a piston assembly operative within said cylinder and movable relative thereto between extended and retracted positions, said piston assembly being adapted to be moved from retracted to extended position under the influence of fluid pressure applied thereto, said piston assembly including nozzle means and means for passing fluid through said assembly to said nozzle means, means for admitting fluid to said cylinder to operate said piston assembly, means for applying retractive force to said piston assembly when said fluid pressure is reduced, first spring seat means carried by said piston assembly, second spring seat means connected with said cylinder, helical spring means coiled about said piston assembly and engaged with both of said spring seAt means for biasing said assembly from extended to retracted position, said first spring seat means is provided by an annular laterally extending flange connected to said piston assembly, and engaged by said spring, said second spring seat means is provided by an annular member encircling said piston assembly which is slidable relative thereto, said member having an annular laterally extending flange engaged by said spring.
 17. The sprinkler of claim 16, wherein said retraction means comprises spring means.
 18. The sprinkler of claim 17, wherein said spring means continues to apply positive pressure on said piston assembly in the direction of retraction after the piston assembly has reached said retracted position.
 19. The sprinkler of claim 16, including an annular sealing member enclosing said piston assembly and sealingly interposed between said assembly and said cylinder, and means connected with said cylinder for holding said sealing member.
 20. The sprinkler of claim 19, wherein said holding means includes a second cylinder disposed within said first cylinder and above said sealing member, the lower end portion of said second cylinder engaging said sealing member and holding it against movement, and means interconnecting the two cylinder and holding said second cylinder against movement. 